ABSTRACT

We present the result of a spectroscopic survey performed in the outskirts of the globular cluster NGC1851 with Visible MultiObject Spectrograph (VIMOS)/Very Large Telescope (VLT) with the medium-resolution grism coupled with the GG475 filter. The spectral coverage is from 5000 to 8000Å with a resolution R~580. Target stars have been selected from the photometry of Carballo-Bello et al. (2012MNRAS.419...14C), sampling a wide range in magnitude and colour (16<B<22, 0.6<B-R<2.1). We report the radial velocities of 107 stars in a region between 12 and 33 arcmin around the cluster centre.

Observations have been performed during three nights in 2008 October at the Very Large Telescope's (VLT) Unit Telescope 3 (Melipal) at the European Southern Observatory (ESO), Cerro Paranal, Chile, equipped with the VIsible MultiObject Spectrograph (VIMOS). Velocities have been obtained by cross-correlating the spectra of the individual exposures with a GIRAFFE solar spectrum smoothed to the resolution of our targets using the region of the H-alpha line. Typical errors are of about 15km/s.